In 1928, the abbot decided to start a weekly 8-page youth supplement, appearing every Thursday. He called it Le Petit Vingtième (The Little Twentieth). Hergé was named Editor-in-Chief. In the first issue, appearing on November 1, 1928, he illustrated a short comic made by Desmedt, the sports editor of the newspaper called Les Aventures de Flup, Nénesse, Poussette et Cochonnet.[3] Sensing that this comic lacked spirit and was rather old-fashioned compared to the current American comics and to the works of Alain Saint-Ogan, Hergé started working on his own comic.[4] In 1927, he met Germaine Kieckens, the secretary of the abbot at the newspaper. They were engaged in 1932[5] and married on July 20 of the same year.[6]

On January 10, 1929, in issue 11, Tintin in the Land of the Soviets began.[7] Every issue featured two pages of the story, and Hergé often made covers for the supplement depicting Tintin as well. A year later, on January 23, 1930, the supplement increased from eight to 16 pages, and the first page of Quick & Flupke, a new gag strip, appeared in the magazine.[8] 310 gags would appear before the paper folded.

The supplement, especially the comics, was an overwhelming success, with circulation of the publication quadrupling on Thursdays.[9] At the end of each of the first three stories of The Adventures of Tintin, an actual reception of the comic hero (played by an actor) at the station in Brussels was organized, with thousands of people attending. The first of these was attended by Zita of Bourbon-Parma, the former empress of Austria, and her children.[10]

In the meantime the first assistants to Hergé were hired to help him fill the supplement and to do minor work on Tintin and Quick & Flupke: Eugène Van Nijverseel, better known as Evany,[7] and Paul Jamin (also signing as Jam).[11]

To capitalize on the success, a new publishing house was started, Les éditions du Petit Vingtième. It published the first three books of Tintin and the first two of Quick & Flupke before folding and passing the rights in 1934 to Casterman, which was better suited to cope with the international success of Tintin (which by then also appeared in France and Switzerland). Both the newspaper comics and the album publications were in black and white, although the covers to the supplement, which were also often made by Hergé, used a supporting colour.

Between February 8 and August 16, 1934, Hergé also published the more juvenile story Les aventures de Popol et Virginie chez les Lapinos (translated as Popol out west).[12] This story was only first published as an album (in French) in 1952 though.[13]

In February 1940, an attempt was made to launch De Bengel, a Dutch translation of Le Petit Vingtième. This magazine marked the first appearance of Tintin in Dutch. The magazine seems to have never been distributed though, and only one copy is known to exist.[14] In the 2011 film, The Adventures of Tintin, Le Petit Vingtième makes an appearance with its French title, but with a front page in English and the Dutch words redactie en beheer ("editorial board and management") visible in the banner.

The publication of Tintin and Quick & Flupke continued in the newspaper supplement until May 1940, when the Germans invaded Belgium.[15]

Between 1930 and 1940, some 310 gags of Quick & Flupke appeared in 'Le Petit Vingtième, all in black and white. They regularly appeared on the cover of the supplement as well. Two albums were published by the Editions du Petit Vingtième. Most of the other gags appeared later at Casterman.